Soundproofing building materials



July 15, 1930. w. A. COLLINGS ET AL I 1,770,767

SOUNDPROOFING BUILDING MATERIALS Filed Nov. 12, 1926 11v NTOR. 1wmbmmliguwms or 035. BY

Patented July 15, 1930 UNiT-ED STATES.

PATENT. oFFrca wmmu a. commas, or sums Ionics, Arm BOY cause, or masscrrm'mnssounr, assreuons 'ro srmca raonucrs 00., or nos moms, camou-KIA, A OOB-POBA'IION (DI-DELAWARE somrnoome surname Application fledl'ovembcr 18, race. W at. 37,941..

This invention relates to the building of i floors, walls andsimilarelements of conwalls wi struction of a character such that thesound reverberations from the walls and transmission through the wallsis limited, and refers more specifically to a construction whichprevents transimssion of sound and also prevents the -re flection ofsound by the use of cellular mineral aggregate held together by a binderin such a way that a maximum of air cells is produced. The problemofmaking a room most satisfactory from an acoustical stand oint consistsin making partition 5 the greatest possible value against sound, at thesame time having them as as possible and structurally strong. Theelement also of preventing re flection of sound from such partitions 1sof great importance. Ordinarily a surface hav ing the greatest abilityto absorb sound iseasily penetrated by sound or-is structurally weak,Another element in such a partition wallconsists in ha a surface whichis sanitary and which owe the penetration of the sound withoutreflection.

As an illustration of this type of partition or structure, Figure Ishows a. cross-sec-' tion of-a partition wall. This partition wallconsists of three elements! (A) is a composition of cellular mineralaggregate held together with a binding agent. This binding agent may behydraulic cenient, Keenes cement or bituminous cement. The cellularmineral aggregate ma 'te or material su be umice,'tufa, a

P atent No. 1,314,752 and asisdesgribedin co-pendin ap lications of thepresent inventors. e binding material may, if dcsired,be emulsified withair so that it sents a maximum number of air to be noted that much ofthe virtueof this cellular mineral lies in the fact that the cells areed gas produced in heating'argillaceous material to incipientintumescence.--' The intumescenceis caused by the expanding of or. watervapor and when the materialcooled PHI-($1083 avacuum exists in ese As isw known, sound cannot travel through a vacuum, and therefore suchsulatintg withaminim'um'of H,

- "This makesit important to acts as a ab .sorbent and alsopenetration-of cellular mineral aggregate offers the ideal inmaterialagainst sound. Small vials or hot es evacuated byahy-means may be usedto furnish the necessary sound insulation cells or cellular agregate.

In addition to offering such properties, this aggregate is structurallyequal to ordinary sand and rock, and when mixed with bituminous binderwill make a structure as stron as one made in a a manner from san androck. For example, Portland cement concrete made with this material willhave a crushing strength, with a mixture of one part of cement, twoparts of fine cellular material and four-parts ob coarse cellularmaterial, at twenty-eight days, of about three thousand unds per squareinch, which is veseen y the same strength as' a sand and Although thisconstruction is-particularlyq desi ed for soundproofing, it has otherbig y. advantageous properties, such as light weight one-half ortwo-thirds that of normal concrete, and a, heat insulation valueinsulating 55 several times that of ordinary. concrete.

While natural cellular material may be used,

it is not as satisiacto as an artificialproduct as hereind -A secondelementin the sound-proof partij tion, is indicated by '(B) in thediagram. :3

Thismaterial is made essentially the same as (A), except that it isdesirable to have the H interstices between mineralparticles largelyfilled with air, and ear-the porti of aamenting materialberelatively'small a w pared with A. Thepurpose ofthisistoallowthesoundtoentertheintersticeswitha 1 of Whilein many in-- stancesthis maybe the exposed orw suriacefof thepartitiom inmostthe too roughand-fliecementation is too slightto-withstandabrasimi add coat (C). Thecoat 3 sound, but not to of A. *The coat G must provideforeasy tion ofsound, its purpose being should'not reflect and should allow easy pene-.

' tration of. sound waves. For this reason, it

as aper, matting, wood pulp, rub

-may be -cemented with plaster of Paris, or

any hydraulic cement or even a bituminous binder of the propercharacter. 'The coat C may be applied in the same way that 'wall paperis applied or in fact; it ma be ordinary wall paper; or it may lieapplied with a brush or Coat B would be applied normally with'atrowel,-A being the structural element applied either in forms or asblocks or tiles. 'In the case of both A and-B, it is always de- 'sirableto use some plasticising agent, such as 'be'ntonite.

This aids in maklng 1t pomible to intermix air with the binder onaccount of increasing the viscosity and the plasticity of the mix;Insteadof using'air, much the same effect is obtained by using a largeamount of the bentonite or gelatinizing clay with a large ainountofwater,the water drying out obtained by putting in the mix limestone dustand hos horic acid, thus forming -carbon dioxi e. ed cell's..

A typical mix for A would be as follows:

.Hydraullc cement, such as Portland cemeut, alumina cement and naturalce-" ment, or plaster or Parls 1 part by volume Fine cellular aggregateof the clue of ordlnary sand retained on I. IO-mesh screen, and made byburning arglllaceous material 2parts Coarse cellular aggregate made byburnin? or aceous material parts Gels nl ng clay 5, at lpart Water 1%parts Atypical finished mix-would have the compositionas follows v a b vl PercentPcrcmt Hydraulic cement. 10 16 Cellular and. 20 20 v i o ii lilul 11 a $3 I 5 I D P 01 D" D 9 P6 6 Wood pulp or brous materiel loose 45 Bentonlte 1 6 spray in the form of an oil varnish.

aflin beforemixing; mixes would be as follows:

We claim as our inve'ntioni prising a section composed of a layer ofrela- 1. soundproof structural elements com-- tivel coarse cellularaggregate,'the cells of;

whic are non-communicative with each other, a second layer bondedthereto,'the

coat on the latter layer low in sound-reflect ing properties. 2.Soundproof structural elements comprising adjacent and bonded layersmade of mineral aggregate, said aggregate having a cellular structurewith a maximum of non- ..c'o mmunicating cells, the'eggregate in one;later to form vo ds. Porosity may also be layer being. of relatively,coarser material than-the other and a surface coat low insound-reflecting properties. 3. soundproof structural elementscomprising adjacent layers made of mineral aggregate having anintra-cellular structure ..the aggregate in one ayer being of relativelycoarser material than the other, and a surface coat-low insound-reflecting properties bonded to the layer of smaller sizedaggregate.

4. Soundproof structural elements comprising adjacent and bonded layersmade of mineral aggregate, said aggregate having-a cellular structurewith aomaxlmum of non-- communicating cells, the aggregate in oneceramic a ltjnw of. relatively f coarser .material l than the aggregatein the other. hfl a lu 1 I 5. Soup proof structural elements. oom- Itisoptional, in some instances, to replace.

-- gpa t of thesand or part ofthe gelatinizing clay with diatomaceouse'arth,-thus giving 'g'reater porosity and" sound absorbing qualities.However,- it. beborne in1 that the sound insulation properties are most..largely, dneto the" 'cells'existing within the aggregate itself.course,"when laster of Paris is used,.the.water content may beconsiderably ."inc'r'eased; lit" may also be. noted thatAmay withor-without either or both Bar 0 on'jeither' or'both sides; I Coats A andB may also include-such bind- :ers and fillers aahair, straw, woo'dpulp, newspapers, or any fibrous or cellular material, ,Pulp pellets,dried and mixed with v "the plaster ooat B yarevery useful in soundabsorption? The wood-pulp pelletsmay be waterproof with waxy materialsuch as percat structure of normal strength containing large percentageof vacuum cells and resists ant to iis-placcda layer withhigh'absorptive an' d .1 p operti s P6 sound,

prising adjacent and bondedlayers made of vsmallersize;

.- 6. Sot1 ndproof see-acid elements as pr s ad a en ye s made P? elmineral .s smsste, ag g e i 'ns' 1 llul r structure amaximum oinorf-comxlnunica t eaggr eg ate 'i n one ayer ofreAtivel coarser,matorialthanithe other.

. p i g '&

the-passageof sound waves, on which smooth surface hig covered by arelativel y penetrative to soun 8. A partition structure comprising abase element resistant to the transmission of sound waves and made fromvacuum celled aggregate held together with a hardened paste ofgelatinizing clay and cement.

9. A partition structure comprisin a supported base element made fromcell ar mineral aggregate held together with a hardened paste ofPortland cement, such base element eing relatively impervious to thepassage of sound waves, a covering of relatively smallsized mineralaggregate and cement mixed and hardened to give a porous structure withpoor sound-reflecting properties.

10. A artition structure comprising a supported base element made fromcellular mineral aggregate held together with a hardened paste ofPortland cement, such base layer in turn bein element being relativelyimpervious to the passage of sound waves, a covering of'relativelysmall-sized mineral aggregate and cement mixed and hardened to give aporous structure with poor sound-reflecting properties.

WILLIAM A. COLLIN GS. ROY GROSS.

